ChemInform Abstract: Synthesis of 1‐Methylbenzimidazoles from Carbonitriles.

Sluiter, Jonas; Christoffers, Jens

doi:10.1002/chin.200920113

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“…Although the Phillip's method is one of the most frequently utilized methods of benzimidazoles synthesis, several variations of this method have been developed (Crotti et al, 1992;Yang et al, 2005;Du and Wang, 2007;Sluiter and Christoffers, 2009; Peng et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Comparative study of 1,3-dibromo-5,5-dimethylhydantoin assisted and conventional synthesis of benzimidazole derivatives and the solvent effects on spectroscopic properties

Segun¹

2015

Afr. J. Pure Appl. Chem.

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A small library of benzimidazoles with a range of side-chain substituents have been synthesized through the condensation reaction of o-phenylenediamine derivatives and several other commercially available materials. The reactions were catalyzed by either 4M HCl or 1,3-dibromo-5,5-dimethylhydantoin (DBDMH). The compounds synthesized using DBDMH as the catalyst required a shorter reaction time, the yield was higher and the workup procedure was not as tedious as those produced using 4M HCl as the catalyst. The structural elucidations of synthesized compounds have been confirmed through spectroscopic analysis.13 C NMR analysis of some of the synthesized compounds showed that the appearance of carbon signals in the NMR spectrum is affected by the nature of the NMR solvent and temperature.The exchange-induced broadening of the 13 C NMR signal was probably facilitated by the intermolecular proton exchange between the NH of the benzimidazole and the H 2 O present in the DMSO-d 6 solvent.Key words: 1,3-dibromo-5,5-dimethylhydantoin, benzimidazole, solvent-effect, structure elucidation, synthetic method. INTRODUCTIONBenzimidazoles have occupied a prominent place in medicinal chemistry due to their significant effect as therapeutics in clinical applications. In fact, they have a long and rich history in organic chemistry and drug discovery (Grimmett, 1996;Orjales et al., 1997 (Wright, 1951). The interest in benzimidazole as a drug molecule began in 1944 when Woolley speculated that benzimidazole, due to its structural resemblance to purine, induced riboflavin deficiency in bacteria (Woolley, 1944). Emerson et al. (1950) cyanocobalamine (vitamin B12) and suggested that this fragment can be considered as the "precursor" of cyanocobalamine. The benzimidazole moiety has been shown to possess several biological activities that includes antiulcer (omeprazole), antifungal (thiabendazole), anti-inflammatory (Benoxaprofen), antihelmintic (albendazole), antifungal (carbendazim), antitumor (bendamustine) and antiviral (enviradine) effects (Pisano et al., 2000).The synthesis of benzimidazoles dates back to 1872 when Hoebrecker synthesized 2,5 (or 2,6)-dibenzimidazole from the reduction of 2-nitro-4-methylacetanilide (Wright, 1951).Three years later, Ladenburg made the same compound by refluxing 3,4-diaminotoluene with acetic acid.However, the conventional method of benzimidazole synthesis, known as the Phillip's method, involves the reaction of 1,2-diaminobenzenewith carboxylic acid in the presence of a mineral acid catalyst to form the corresponding substituted benzimidazole (Phillips, 1928). Although the Phillip's method is one of the most frequently utilized methods of benzimidazoles synthesis, several variations of this method have been developed (Crotti et al., 1992;Yang et al., 2005;Du and Wang, 2007;Sluiter and Christoffers, 2009; Peng et al., 2010).In a bid to improve yields and reaction conditions, it is conceivable to develop a series of benzimidazole derivatives using 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) as an effici...

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Section: Introductionmentioning

confidence: 99%